U.S. Pat. No. 4,917,978, issued on Apr. 17, 1990, to Ritt et al., describes a method of manufacturing a screen assembly for a CRT by the electrophotographic screening (EPS) process. The method described in the aforementioned patent includes a "fusing" step followed by a "fixing" step to increase the adherence of the phosphor screen elements to an underlying organic photoconductive (OPC) layer deposited on the interior surface of the CRT faceplate panel. In the fusing step, vapors of a solvent are permitted to contact and soak the OPC layer and the polymeric coupling agent that coats the phosphor materials, to render the layer and the coating tacky. Vapor soaking takes on the order of 4 to 24 hours. The panels are then dried and "fixed" by spraying multiple layers of polyvinyl alcohol (PVA) in an alcohol-water mixture onto the fused phosphor elements. Each spray application requires about 2 to 5 minutes to achieve complete screen coverage. The "fixed" screens are then filmed, either by convention spray or emulsion filming. It has been determined that the PVA spray applications tend to move the phosphor elements slightly, which night be unacceptable, depending on the amount of movement.
U.S. Pat. No. 5,474,866, issued on Dec. 12, 1995 to Ritt et al., describes a method for fixing the phosphor elements to the underlying OPC layer, by electrostatically spraying a suitable fixative. The fixative dissolves the polystyrene of the OPC layer in such a manner that the phosphor elements are at least partially encapsulated by the OPC layer, without causing any movement of the phosphors. However, using the process of U.S. Pat. No. 5,474,866, it is very difficult to fix the screen uniformly across the panel surface on a consistent basis. The polystyrene of the OPC layer 34 is completely soluble in the fixatives amyl acetate, butyl acetate, MIBK, toluene and xylene, and partially soluble in acetone, the former all having a boiling point within the range of 100 to 150.degree. C. MIBK has been the preferred fixative because it dissolves the polystyrene of the OPC layer 34 more slowly than the other solvents, and encapsulates the phosphor elements without moving them. However, screens fixed with MIBK contain under and over fixed areas within the same panel, thereby adversely affecting the subsequent film uniformity.